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Last fall, the world was excited by the discovery of an exoplanet called Ross 128b, which lies 11 light-years from Earth. New work from a team led by Diogo Souto of the Brazilian National Observatório and including Johanna Teske from Carnegie have for the first time determined the detailed chemical abundances of the planet's star host, Ross.
Understanding what elements are present in a star can help researchers estimate the composition of the exoplanets that orbit them, which can help predict the resemblance of planets to the Earth. "Until recently, it was difficult to obtain detailed chemical abundances for this type of star," says author Souto, who has developed a technique for doing these measurements. Last year
As the host star of the Ross exoplanet 128, about 70% of the Milky Way's stars are red dwarfs, much colder and smaller than our Sun. Based on the results of extensive global prospecting campaigns, astronomers believe that many of these red dwarf stars harbor at least one exoplanet. Several planetary systems around red dwarfs have been new makers in recent years, including Proxima b, a planet that revolves around the nearest star of our own Sun, Proxima Centauri, and the seven planets of TRAPPIST- 1. Using the APOGEE spectroscopic instrument of Sloan Digital Sky Survey, the team measured the near-star-infrared light to determine the abundance of carbon, air and water. 39, oxygen, magnesium, aluminum, potbadium, calcium, titanium and iron
. "APOGEE's ability to measure near-infrared light, where Ross 128 is the brightest, was the key to this study," Teske said. "This allowed us to answer some basic questions about Ross's" Earth-like "128b," says Teske
when the stars are young, they are surrounded by a disc of gas and dust in rotation. The chemistry of the star can influence the contents of the disc, as well as the mineralogy and the inner structure of the resulting planet. For example, the amount of magnesium, iron, and silicon in a planet will control the mbad ratio of its inner core and mantle layers.
The team determined that Ross 128 has iron levels similar to our Sun. Although they could not measure its abundance of silicon, the ratio of iron to magnesium in the star indicates that the nucleus of its planet, Ross 128b, should be larger than that of Earth.
and stellar abundance, the team also was able to estimate a range for the radius of the planet, that it is not possible to measure directly because of the l? Orbit orientation of the planet around the star
to understand what it is made of, because these two measurements can be used to calculate its apparent density. Moreover, by quantifying planets in this way, astronomers have realized that planets with radii greater than about 1.7 times the Earth are probably surrounded by a gaseous envelope, such as Neptune, and those with more radii. smaller are more rocky, like our
The estimated radius of Ross 128b indicates that it should be rocky.
Finally, by measuring the temperature of Ross 128 and estimating the radius of the planet, the team was able to determine how much of the light of the host star should be reflected on the surface of Ross 128 b, revealing that our second closest rocky neighbor probably has a temperate climate
"It's exciting what we can learn about another planet is telling us about the chemistry of the system," said Souto. that Ross 128b is not the twin of the Earth, and we are still unaware of its potential geological activity, we have been able to reinforce the argument that it is a temperate planet that could potentially have l & # 39; water on its surface. "19659014] !! Function (f, b, e, v, n, t, s) {if (f.fbq) returns; n = f.fbq = function () {n.callMethod?
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